1. Technical Field
The present disclosure generally relates to wellbore servicing fluids. More particularly, this disclosure relates to viscoelastic surfactants and methods of making and using same.
2. Background
Natural resources such as gas, oil, and water residing in a subterranean formation or zone are usually recovered by drilling a wellbore down to the subterranean formation while circulating a drilling fluid in the wellbore. During the drilling of a well bore a drilling fluid may be circulated down through the inside of the drill string, through the drill bit, and to the surface through the annulus between the walls of the well bore and the drill string. The drill string may be a drill pipe, a casing string, or any other suitable conduit. Among other things, the circulating drilling fluid lubricates the drill bit, carries drill cuttings to the surface, and balances the formation pressure exerted on the well bore. One problem associated with the drilling of a well bore may be the undesirable loss of large amounts of the drilling fluid into the subterranean formation. This problem may be referred to as “lost circulation” and the sections of the formation into which the drilling fluid is lost are referred to as “lost circulation zones.” In addition to drilling fluids, problems with lost circulation may also be encountered with other fluids, for example, spacer fluids, completion fluids (e.g., brines) and workover fluids that may be circulated in a well bore. Herein a spacer fluid refers to any liquid used to physically separate one special-purpose liquid from another; a completion fluid refers to a solids-free liquid used to facilitate final operations prior to initiation of production; and a workover fluid refers to a well-control fluid, that is used during the performance of maintenance or remedial treatments on a hydrocarbon producing well. A variety of factors may be responsible for lost circulation. For example, the subterranean formation penetrated by the well bore may be highly permeable or may contain fractures or crevices therein. Furthermore, the formation may breakdown under the hydrostatic pressure applied by the fluid, thereby allowing the fluid to be lost into the formation. For instance, fractures in the subterranean formation may be created or enhanced due to the hydrostatic pressure of the drilling fluid with the resulting loss of drilling fluid into those fractures.
A number of methods have been developed to control lost circulation. One method commonly used to control lost circulation involves the placement of lost circulation materials into the lost circulation zone. These lost circulation materials may be placed into the formation for example as lost circulation pills in an attempt to control and/or prevent lost circulation. Conventional lost circulation pills may suffer from a variety of drawbacks such as the large amount of materials needed to achieve desired properties (e.g., viscosities, etc.) and difficulties associated with removing the component materials of the pill once the treatment has been completed. Thus, it would be desirable to develop improved compositions for controlling lost circulation.